The Mysterious Origin of (and Disturbing Problems with) the "Wolf Whistle"

It's one of those iconic 'you know it when you hear it' sounds - the two-note whistle made famous in old Tex Avery cartoons and multiple films of yesteryear. But what is the wolf whistle? Where did it actually come from, and how did it go from being such a popular trope to something (thankfully) so rare in the modern day?

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